[Serum and urine prostate-specific antigen ratio: its value in the distinction between prostate cancer and adenoma when serum prostate-specific antigen level is between 4 and 10 ng/ml].

Background: In an earlier study, we demonstrated that benign prostatic hyperplasia (BPH) was associated with significantly higher urine levels of prostate-specific antigen (PSA) than in prostate cancer (PC). These early results led to the present study: we assessed, in patients undergoing a prostate biopsy, the clinical value of the PSA serum/urine ratio (PSA S/U) in patients for the differential diagnosis of PC, particularly when the pre-biopsy serum level of PSA lies between 4.0 and 10.0 ng/ml.

Methods: All patients without an indwelling drain who underwent transrectal echoguided biopsy were prospectively included in this study from November 1994 to December 1995. All serum and urine PSA measurements were done by the same laboratory using a Tandem R kit (Hybritech). Blood and urine samples were obtained during the 24 hour period prior to surgery during which all urethral or rectal manipulation was avoided.

Results: We studied 130 patients with BPH (n = 73) or PC (n = 57). The PSA serum levels and the PSA S/U were significantly different between the BPH and the PC groups. In the subgroup of 50 patients with a serum PSA level in the 4-10 ng/ml range, the difference between the BPH and PC patients was not significantly different except for the PSA S/U ratio. Receiver operating characteristic (ROC) curves showed that the diagnostic power of PSA S/U was greater than serum PSA.

Conclusion: These results suggest that the PSA S/U ratio could be useful to distinguish between BPH and PC, particularly when diagnosis is uncertain in patients whose serum PSA is in the 4.0-10.0 ng/ml range.